The present invention relates to integrated components, and more particularly to integrated capacitors having low values and high Q which are suitable for bandpass filters.
There are many electronic devices which require bandpass filters. These filters may be cascaded together and coupled one to the other by coupling capacitors. These circuits generally are built with discrete components, especially where resonant frequency filters are concerned. These circuits have a coil, fixed capacitor and variable, or tuning, capacitor connected in parallel, with each stage coupled to the next by a coupling capacitor. At frequencies in the range of one hundred megahertz the value of this coupling capacitor is required to be small, on the order of tenths of picofarads. With discrete components it is difficult to reliably get capacitors of very small value with high Q, and these components have an impact on the frequency performance of the circuit due to lead lengths and position.
Therefore, it is desired to have for use in bandpass filters integrated capacitors of very small value which have a high Q without the frequency sensitivity demonstrated by discrete components.